WASHINGTON -- The government's senior auditor, Charles A. Bowsher, said yesterday that a new prediction of a savings and loan bailout costlier and longer than officially recognized suggests that the administration may be putting off its true costs until after the presidential election next year.

"What the administration is asking for is enough working capital and loss funds to get through the election and into 1993," said Mr. Bowsher, the comptroller general. "It's not at all clear that it will be enough."

Mr. Bowsher spoke during a break in an appearance before a House banking subcommittee.

His comment came after Robert D. Reischauer, director of the Congressional Budget Office, told the lawmakers that the bailout costs would total $191 billion, in terms of actual annual losses, from 1989 to 1996, which would be $31 billion more than the administration has said would be necessary.

Treasury officials have steadfastly denied that they are playing politics with the financing by underestimating the costs until after the election.

They have said in recent weeks that they expected a new $80 billion appropriation this fall to be sufficient -- perhaps even be more than necessary -- to complete the job.

At a hearing last week, Deputy Treasury Secretary John E. Robson, noting that the administration had been criticized for past estimates, said it had taken special care to assure as accurate an estimate as possible.

"While CBO does not have enough information about the administration's latest estimates to make a precise comparison," Mr. Reischauersaid, "our analysis suggests that the final costs of resolution will be higher, more institutions will be closed, and the cleanup job will take longer than the administration anticipates."

His forecasts in a wide variety of areas are considered objective enough to provide the basis for legislation sponsored by both Democrats and Republicans.

Mr. Reischauer said the Resolution Trust Corp. probably would be resolving the plight of failed institutions through early 1995, three years beyond the period initially contemplated by Congress and the administration.

He estimated that 1,500 savings associations would have to be closed or merged ultimately, which was lower than his previous estimate of up to 1,700 but still substantially above the administration's projection of 1,000 institutions.

Since August 1989, the RTC has seized 651 institutions and sold, merged or liquidated 536 of them.

Measuring the entire expense in terms of 1990 dollars and unadjusted for inflation, Mr. Reischauer estimated that the bailout would cost $155 billion.